It is known that compositions comprising the tunica submucosa of the intestine of warm-blooded vertebrates can be used advantageously as tissue graft materials. See U.S. Pat. Nos. 4,902,508 and 5,281,422. The tissue graft compositions described in those patents are characterized by excellent mechanical properties, including high compliance, a high burst pressure point, and an effective porosity index which allows such compositions to be used beneficially for vascular graft and connective tissue graft constructs. When used in such applications the graft constructs appear not only to serve as a matrix for the regrowth of the tissues replaced by the graft constructs, but, indeed, to promote or induce such regrowth of endogenous tissue. Common events to this remodeling process include: widespread and very rapid neovascularization, proliferation of granulation mesenchymal cells, biodegradation/resorption of implanted intestinal submucosal tissue material, and lack of immune rejection.
It is also known that intestinal submucosa can be fluidized by comminuting and/or protease digestion, without loss of its apparent biotropic properties, for use in less invasive methods of administration (e.g., by injection or topical application) to host tissues in need of repair. See U.S. Pat. No. 5,275,826.
There has been much additional research effort directed to finding other natural and synthetic materials having the requisite properties for use as tissue grafts. Surprisingly, it has been found that urinary bladder submucosa (UBS) prepared by delamination of bladder tissue of warm-blooded vertebrates exhibits mechanical and biotropic properties similar to that which has been reported for intestinal submucosal tissue. It can be substituted for intestinal submucosa tissue in most, if not all, of the applications previously reported for intestinal submucosa.
The tissue graft composition of the present invention comprises urinary bladder submucosa derived from urinary bladder tissue of a warm-blooded vertebrate. The wall of the urinary bladder is composed of the following layers: the tunica mucosa (including a transitional epithelium layer and the tunica propria), a submucosa layer, up to three layers of muscle and the adventitia (a loose connective tissue layer)--listed in thickness crossection from luminal to abluminal sides. Urinary bladder submucosa for use in accordance with the present invention is delaminated from the abluminal muscle layers and at least the luminal portion of the tunica mucosa of the urinary bladder tissue. The present graft composition can be implanted or injected into a vertebrate host to induce the repair or replacement of damaged or defective tissues.